Adaptive link annotation is one of the most popular adaptive educational hypermedia techniques. It has been widely studied and has demonstrated its ability to help students acquire knowledge faster, improve learning outcomes, reduce navigation overhead, increase motivation, and encourage the beneficial non-sequential navigation. However, almost all studies of adaptive link annotation have been performed in the context of dedicated adaptive educational hypermedia systems. The value of this technique in the context of widely popular learning portals has not yet been demonstrated. In this paper, we attempt to fill this gap by investigating the value of adaptive navigation support embedded into the learning portal. We compare the effect of portal-based adaptive navigation support on both the effect of the adaptive navigation support in adaptive educational hypermedia systems and to non-adaptive learning portals.